DST(Daylight Saving Time) Setting

Daylight Saving Time (DST) is the practice of advancing clocks during the summer months by one hour so that light extends into the evening hours—sacrificing normal sunrise times. Typically, users of DST adjust clocks forward one hour near the start of spring and adjust them backward in the autumn to regular time.

When importing the tag data from RTDB, DST is considered at DST start date and DST end date if the tag was not adjusted in RTDB.

The DST start date and end date can be configured in the Utility tab in Option window.

AVEVA Production Accounting initially gets the DST start date and end date from Window System.

The following steps describe how to change the DST Start Date and End Date:

• Type the new date and then save this date into the AVEVA Production Accounting database by clicking Save DST Date Info. Into the Database button. User can save these data once a year before DST starts.

• If the saved DST date information was wrong, select the wrong DST date and then remove it by clicking Remove DST Date Info. from the Database button.

  

And then when user select the period, AVEVA Production Accounting checks whether the date of the selected period is on DST Start Date or DST End Date.

After defining DST info, the syntax of RTDB tag name shall be changed in "Edit Tag Information" window if the tag need to be considered DST.

If the tag name is A.PV, the tag name shall be changed into A.PV;DST.

It means if the tag needs to be considered DST, we changed the tag name followed by semicolon & DST.

For example of calculation tag, if A.PV tag needs DST correction and B.PV tag does not need DST correction and so the current equation of the calculation tag is Tag(A.PV)+Tag(B.PV), the equation shall be changed as Tag(A.PV;DST)+Tag(B.PV).

If the selected period is on DST Start Date, when user gets the tag data from RTDB, the tag value shall change into 23/24*original tag value.

If the selected period is on DST End Date, the tag value shall be changed into 25/24*original tag value.